She sent me details of the solar or photic sneeze reflex. It turns out about a quarter of people experience a prickling sensation or sneezing when exposed to bright light. Someone has even managed to concoct an acronym to label it ‘ACHOO’ syndrome!

A number of medical papers have been published on the subject. One describes an experiment where an EEG machine measured the brain activity of test subjects, while they looked at a bright flashing light. The ‘photic sneezers’ were seen to have ‘a generally enhanced excitability of the visual cortex, In addition a stronger pricking sensation in the noses of photic sneezers was found to be associated with activation in the insula and stronger activation in the secondary somatosensory cortex’.

It seems there is some neurological link between the eyes and nose, perhaps with a genetic aspect, but the exact cause and reason of reflex is still unclear.

It is more than just a curiosity though. One piece of research considers the risks for combat pilots whose enemies favour attacking ‘out of the sun’ and so this part of the sky must be watched.

I speculated to Dr Han that the inability of a person with aniridia to block out bright light could make them more likely to experience the reflex if they have it. I suggested that this could be subject of another research study!

But anecdotally do you (or your child) with aniridia get a prickly nose or sneeze when it is too bright?